Kumar, Mahesh and Rajpalke, Mohana K and Roul, Basanta and Bhat, Thirumaleshwara N and Misra, P and Kukreja, LM and Sinha, Neeraj and Kalghatgi, AT and Krupanidhi, SB (2011) Temperature-dependent photoluminescence of GaN grown on beta-Si3N4/Si (111) by plasma-assisted MBE. In: Journal of Luminescence, 131 (4). pp. 614-619.
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Photoluminescence (PL) of high quality GaN epitaxial layer grown on beta-Si3N4/Si (1 1 1) substrate using nitridation-annealing-nitridation method by plasma-assisted molecular beam epitaxy (PA-MBE) was investigated in the range of 5-300 K. Crystallinity of GaN epilayers was evaluated by high resolution X-ray diffraction (HRXRD) and surface morphology by Atomic Force Microscopy (AFM) and high resolution scanning electron microscopy (HRSEM). The temperature-dependent photoluminescence spectra showed an anomalous behaviour with an `S-like' shape of free exciton (FX) emission peaks. Distant shallow donor-acceptor pair (DAP) line peak at approximately 3.285 eV was also observed at 5 K, followed by LO replica sidebands separated by 91 meV. The activation energy of the free exciton for GaN epilayers was also evaluated to be similar to 27.8 +/- 0.7 meV from the temperature-dependent PL studies. Low carrier concentrations were observed similar to 4.5 +/- 2 x 10(17) Cm-3 by measurements and it indicates the silicon nitride layer, which not only acts as a growth buffer layer, but also effectively prevents Si diffusion from the substrate to GaN epilayers. The absence of yellow band emission at around 2.2 eV signifies the high quality of film. The tensile stress in GaN film calculated by the thermal stress model agrees very well with that derived from Raman spectroscopy. (C) 2010 Elsevier B.V. All rights reserved.
|Item Type:||Journal Article|
|Additional Information:||Copyright of this article belongs to Elsevier Science B.V.|
|Department/Centre:||Division of Chemical Sciences > Materials Research Centre|
|Date Deposited:||06 May 2011 05:57|
|Last Modified:||06 May 2011 05:57|
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